As an example of a group-III nitride semiconductor light emitting element, there are an embedded light emitting element in which a contact electrode is embedded in a light emitting element and a grooved light emitting element and a grooved light emitting element in which a contact electrode is simply formed on a contact layer that is exposed by digging a groove. For example, the embedded light emitting element is disclosed in JP-A-2011-216514 (see, FIG. 2, etc.).
In the light emitting element disclosed in JP-A-2011-216514, a p-contact electrode (109) and an n-contact electrode (103) are embedded in the light emitting element. Further, the p-contact electrode (109) and the n-contact electrode (103) are formed to sandwich a thin insulating film (110) therebetween. Here, the p-contact electrode (109) is formed over the entire region of a light emitting surface.
Therefore, in the light emitting element disclosed in JP-A-2011-216514, there are sites where the p-contact electrode (109) and the n-contact electrode (103) are opposed to each other via the thin insulating film (110) (see, FIG. 2, etc., in JP-A-2011-216514). Accordingly, in these sites, a strong electric field is formed between the p-contact electrode (109) and the n-contact electrode (103).
In the light emitting element disclosed in JP-A-2011-216514, there is a possibility that leakage occurs at the site of the thin insulating film (110). When this light emitting element is used continuously, metal atoms move along the grain boundary of the thin insulating film (110) and a path connecting the p-contact electrode (109) and the n-contact electrode (103) to each other is formed whereby there is a possibility that the leakage current occurs. Further, the service life of the light emitting element is short. In addition, there is a possibility that initial failure occurs. That is, the yield is poor.
On the other hand, in the grooved light emitting element, as described in more detail at the comparison between the illustrative embodiments (to be described later) and a conventional example, originally, there is little possibility that the p-contact electrode and the n-contact electrode are conducted to each other even when the insulating film is not provided. Accordingly, the following issues are unique to the embedded light emitting element.
The present invention has been made to solve the above-described problems of a prior art. That is, an object of the present invention is to provide a group-III nitride semiconductor light emitting element that is capable of suppressing the occurrence of leakage current in an embedded element where a contact electrode is disposed in a state of being embedded between a semiconductor layer and a support substrate and a manufacturing method therefor.
[1] According to an aspect of the invention, a group-III nitride semiconductor light emitting element includes a semiconductor layer that includes a light emitting layer, a p-type semiconductor layer and an n-type semiconductor layer, a p-contact electrode that is in contact with the p-type semiconductor layer, an n-contact electrode that is in contact with the n-type semiconductor layer, and a support substrate that supports the semiconductor layer. The p-contact electrode and the n-contact electrode are disposed at a position between the semiconductor layer and the support substrate. In a case where the p-contact electrode and the n-contact electrode are orthogonally projected on a plate surface of the support substrate, the p-contact electrode and the n-contact electrode are formed in a shape in which the orthogonally projected p-contact electrode and the orthogonally projected n-contact electrode are not overlapped with each other.
In the group-III nitride semiconductor light emitting element, an electric field in a direction perpendicular to a light extraction surface is not applied between the p-contact electrode and the n-contact electrode. Accordingly, initial failure is reduced and therefore the yield is good. Further, there is little possibility that leakage current occurs between the p-contact electrode and the n-contact electrode by continuous use.
[2] The group-III nitride semiconductor light emitting element of [1] further includes a first passivation film disposed at a position between the p-contact electrode and the n-contact electrode.
At this time, the first thin passivation film is in a position between the p-contact electrode and the n-contact electrode. However, the p-contact electrode and the n-contact electrode do not face each other through the first passivation film. Therefore, there is little possibility that a strong electric field is formed in a film thickness direction of the first passivation film. Accordingly, the occurrence of leakage current is suppressed.
[3] In the group-III nitride semiconductor light emitting element of [1] or [2], the p-contact electrode includes a comb-like p-wiring electrode part, the n-contact electrode includes a comb-like n-wiring electrode part, and in a case where the p-wiring electrode part and the n-wiring electrode part are orthogonally projected on the plate surface of the support substrate, the orthogonally projected p-wiring electrode part and the orthogonally projected n-wiring electrode part are arranged to be engaged with each other.
Since the p-contact electrode and the n-contact electrode are arranged to be engaged with each other in a comb-like shape, the current is sufficiently diffused in the light emitting layer. Therefore, light emitting efficiency is good.
[4] The group-III nitride semiconductor light emitting element of any one of [1] to [3], further includes a first metal layer that is in contact with the p-contact electrode. In a case where the first metal layer and the n-contact electrode are orthogonally projected on the plate surface of the support substrate, the first metal layer and the n-contact electrode are formed in a shape in which the orthogonally projected first metal layer and the orthogonally projected n-contact electrode are not overlapped with each other.
Therefore, there is little possibility that leakage current occurs between the first metal layer and the n-contact electrode.
[5] The group-III nitride semiconductor light emitting element of [4] includes a p-pad electrode that is formed on the first metal layer and an n-pad electrode that is formed on the n-contact electrode. The p-pad electrode and the n-pad electrode are exposed on a surface opposite to the side where the support substrate is disposed, as seen from the semiconductor layer.
[6] The group-III nitride semiconductor light emitting element of [4] or [5] further includes a bonding layer that is located between the first metal layer and the support substrate and containing solder, and a second metal layer that is formed over the entire surface of the bonding layer on the semiconductor layer side. The second metal layer is a cover metal layer for preventing the solder contained in the bonding layer from being diffused toward the first metal layer.
[7] The group-III nitride semiconductor light emitting element of [6] further includes a second passivation film that is formed over the entire surface of the second metal layer on the semiconductor layer side.
[8] The group-III nitride semiconductor light emitting element of any one of [1] to [7] further includes a reflective film that is disposed at a position between the semiconductor layer and the support substrate. In a case where the reflective film, the p-contact electrode and the n-contact electrode are orthogonally projected on the plate surface of the support substrate, the orthogonally projected reflective film is disposed at a position between the orthogonally projected p-contact electrode and the orthogonally projected re-contact electrode.
[9] A method of manufacturing a group-III nitride semiconductor light emitting element includes a semiconductor layer forming process for growing a semiconductor layer including a light emitting layer, a p-type semiconductor layer and an n-type semiconductor layer on a grow substrate, a recess forming process for forming a recess on the semiconductor layer from the p-type semiconductor layer side to expose a portion of the n-type semiconductor layer, an n-contact electrode forming process for forming an n-contact electrode on the n-type semiconductor layer that is exposed to the recess, a p-contact electrode forming process for forming a p-contact electrode on the p-type semiconductor layer, a bonding process for bonding a laminate including a support substrate to a base material including the semiconductor layer from the position opposite to the growth substrate to form a bonding body and, a growth substrate removal process for removing the growth substrate from the bonding body. In the n-contact electrode forming process and the p-contact electrode forming process, in a case of being orthogonally projected on a plate surface of the support substrate, the p-contact electrode and the n-contact electrode are formed in a shape in which the orthogonally projected p-contact electrode and the orthogonally projected n-contact electrode are not overlapped with each other, and in the bonding process, the p-contact electrode and the n-contact electrode are bonded so as to be disposed at a position between the semiconductor layer and the support substrate.
[10] The method of manufacturing the group-III nitride semiconductor light emitting element according to [9] further includes a passivation film forming process for forming a passivation film that insulates between the p-contact electrode and the n-contact electrode.
According to the present invention, it is possible to provide a group-III nitride semiconductor light emitting element that is capable of suppressing the occurrence of leakage current in an embedded element where the contact electrode is disposed in a state of being embedded between the semiconductor layer and the support substrate and a manufacturing method therefor.